Earlier quoted context omitted.
The problem with your logic is giving private companies complete rights over your physical person once you enter their plane will (and does as shown by the incident) lead to abuse for profit. There was no security issue, there was no emergency, there was no legitimate reason to remove this person from the plane. The abuse and physical harm of a passenger was done entirely in the name of saving a few dollars by not se…
The thing is, on a plane the crew is king and you have to follow their orders. If they decide that you have to leave the plane, you must leave the plane. Now, their reasons might be questionable. You have every right to fight the airline once you are off the plane. But there is no room for this while on board. Basically, as soon as he started to refuse to follow the crew's orders, it was a lost case for him.
Harming a passenger when you had a peaceful solution available is the exact opposite of what they are meant to do.